ionic: monitor fw status generation

The top 4 bits of the fw_status in dev_info_regs is reserved
for the status generation.  This generation number is an
arbitrary value defined when firmware starts up.  If the FW
is killed/crashed/stopped and then restarted, it will create
a different generation number.  With this mechanism, the host
driver can detect that the FW has crashed and restarted, and
the driver can then take steps to re-initialize its connection.
Signed-off-by: Shannon Nelson <snelson@pensando.io>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/pensando/ionic/ionic_dev.c

@@ -106,6 +106,8 @@ int ionic_dev_setup(struct ionic *ionic)
 	idev->last_fw_hb = 0;
 	idev->fw_hb_ready = true;
 	idev->fw_status_ready = true;
+	idev->fw_generation = IONIC_FW_STS_F_GENERATION &
+			      ioread8(&idev->dev_info_regs->fw_status);
 
 	mod_timer(&ionic->watchdog_timer,
 		  round_jiffies(jiffies + ionic->watchdog_period));
@@ -121,7 +123,9 @@ int ionic_heartbeat_check(struct ionic *ionic)
 {
 	struct ionic_dev *idev = &ionic->idev;
 	unsigned long check_time, last_check_time;
-	bool fw_status_ready, fw_hb_ready;
+	bool fw_status_ready = true;
+	bool fw_hb_ready;
+	u8 fw_generation;
 	u8 fw_status;
 	u32 fw_hb;
 
@@ -140,9 +144,29 @@ int ionic_heartbeat_check(struct ionic *ionic)
 
 	/* firmware is useful only if the running bit is set and
 	 * fw_status != 0xff (bad PCI read)
+	 * If fw_status is not ready don't bother with the generation.
 	 */
 	fw_status = ioread8(&idev->dev_info_regs->fw_status);
-	fw_status_ready = (fw_status != 0xff) && (fw_status & IONIC_FW_STS_F_RUNNING);
+
+	if (fw_status == 0xff || !(fw_status & IONIC_FW_STS_F_RUNNING)) {
+		fw_status_ready = false;
+	} else {
+		fw_generation = fw_status & IONIC_FW_STS_F_GENERATION;
+		if (idev->fw_generation != fw_generation) {
+			dev_info(ionic->dev, "FW generation 0x%02x -> 0x%02x\n",
+				 idev->fw_generation, fw_generation);
+
+			idev->fw_generation = fw_generation;
+
+			/* If the generation changed, the fw status is not
+			 * ready so we need to trigger a fw-down cycle.  After
+			 * the down, the next watchdog will see the fw is up
+			 * and the generation value stable, so will trigger
+			 * the fw-up activity.
+			 */
+			fw_status_ready = false;
+		}
+	}
 
 	/* is this a transition? */
 	if (fw_status_ready != idev->fw_status_ready) {

drivers/net/ethernet/pensando/ionic/ionic_dev.h

@@ -143,6 +143,7 @@ struct ionic_dev {
 	u32 last_fw_hb;
 	bool fw_hb_ready;
 	bool fw_status_ready;
+	u8 fw_generation;
 
 	u64 __iomem *db_pages;
 	dma_addr_t phy_db_pages;

drivers/net/ethernet/pensando/ionic/ionic_if.h

@@ -2936,6 +2936,8 @@ struct ionic_hwstamp_regs {
  * @asic_type:       Asic type
  * @asic_rev:        Asic revision
  * @fw_status:       Firmware status
+ *			bit 0   - 1 = fw running
+ *			bit 4-7 - 4 bit generation number, changes on fw restart
  * @fw_heartbeat:    Firmware heartbeat counter
  * @serial_num:      Serial number
  * @fw_version:      Firmware version
@@ -2949,7 +2951,8 @@ union ionic_dev_info_regs {
 		u8     version;
 		u8     asic_type;
 		u8     asic_rev;
-#define IONIC_FW_STS_F_RUNNING	0x1
+#define IONIC_FW_STS_F_RUNNING		0x01
+#define IONIC_FW_STS_F_GENERATION	0xF0
 		u8     fw_status;
 		u32    fw_heartbeat;
 		char   fw_version[IONIC_DEVINFO_FWVERS_BUFLEN];